Turbine blade

ABSTRACT

A turbine blade ( 1 ) includes a plurality of rows of cooling portions ( 4, 4 A,  4 B) that have notch portions ( 41 ) that discharge cooling gas that has been introduced into an internal portion ( 25 ) of a blade portion ( 2 ) onto a ventral side blade surface ( 23 ), and that are formed in rows that are stacked in a direction between the blade front edge and the blade rear edge. This turbine blade ( 1 ) is provided with: turbulence promoting cooling portions ( 4 B) that are provided in the row located furthest to the downstream side from among the plurality of rows, and that have turbulence promoting devices ( 44, 45, 46 ) in areas exposed by the notch portions ( 41 ); and film cooling portions ( 4 A) that are provided in at least one of other rows from among the plurality of rows, and that form a film cooling layer in the areas exposed by the notch portions ( 41 ).

TECHNICAL FIELD

The present invention relates to a turbine blade. Priority is claimed onJapanese Patent Application No. 2011-054253, filed Mar. 11, 2011, thecontents of which are incorporated herein by reference.

TECHNICAL BACKGROUND

Turbine blades that are provided in a turbine are generally exposed tohigh-temperature fluid bodies. In particular, because the turbine bladesprovide in gas turbines are exposed to high-temperature combustion gasthat has been discharged from a combustion chamber, they are exposed toan extremely high-temperature environment. In order to increase thedurability of turbine blades that are exposed to this type ofhigh-temperature environment, in some cases a cooling gas such ascooling air is supplied to the interior of the turbine blades. Bysupplying cooling gas to the interior of the blades in this manner, itis possible to suppress any rise in the temperature of the turbineblades, and to thereby improve the durability of the turbine blades.

It is desirable for the thickness of an area around the rear edge of aturbine blade to be as thin as possible from the standpoint of theaerodynamic performance of the turbine. For this reason, in many casesit is difficult to form a flow path in the area around the rear edge ofa turbine blade to enable the cooling gas to flow into the interior ofthe turbine blade. Namely, the area around the rear edge of a turbineblade can be said to be an area that is difficult to cool. Because ofthis, in, for example, Patent document 1 and Patent document 2, atechnique is proposed in which the rear edge area is made thinner byforming notch portions in the ventral side of the rear edge area of aturbine blade, and film cooling is performed on the rear edge area byblowing cooling gas onto the ventral side surface that is exposed bythese notch portions.

DOCUMENTS OF THE PRIOR ART Patent Documents

-   [Patent document 1] Japanese Unexamined Patent Application, First    Publication No. 2003-56301-   [Patent document 2] U.S. Pat. No. 5,215,431

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, in the techniques proposed in Patent document 1 and Patentdocument 2, it is difficult to adequately cool the area around the rearedge of a turbine blade, and further improvements in the coolingefficiency in the area around the rear edge portion of a turbine bladeare desired. For example, it is possible to increase the heat transferrate between the blade portion and the cooling gas by generatingturbulence in the flow of the cooling gas discharged from the notchportions. However, if turbulence is generated in the flow of thiscooling gas, then this has the disadvantage that the cooling gas getsimmediately mixed into the main flow that is flowing over the surface ofthe blade portions, so that the temperature of the cooling gas that isserving as a refrigerant is raised. Namely, if the turbulence in thecooling gas is promoted more than is necessary, then the mixing of thefilm cooling layer with the main flow gas is accelerated, and theefficiency of the film cooling is deteriorated.

The present invention was conceived in view of the above-describedproblems, and it is an object thereof to improve the cooling efficiencyin an area around the rear edge of a turbine blade by suppressing anydeterioration in the film cooling efficiency in the turbine blade, andby improving the heat transfer rate between the blade portion and thecooling gas.

Means for Solving the Problem

The present invention employs the following structure as a means ofsolving the above-described problems.

A first aspect of the present invention is a turbine blade that isprovided with a plurality of rows of cooling portions that have notchportions that discharge cooling gas that has been introduced into aninternal portion of a blade portion onto a ventral side blade surface,and that are formed in rows that are stacked in a direction between theblade front edge and the blade rear edge, and that includes: turbulencepromoting cooling portions that are provided in the row located furthestto the downstream side from among the plurality of rows, and that haveturbulence promoting devices in areas exposed by the notch portions; andfilm cooling portions that are provided in at least one of other rowsfrom among the plurality of rows, and that form a film cooling layer inthe areas exposed by the notch portions.

A second aspect of the present invention is the turbine blade accordingto the first or second aspects wherein, in at least one of the pluralityof rows, the plurality of cooling portions are placed discretely fromeach other in the height direction of the blade portion.

A third aspect of the present invention is the turbine blade accordingto any of the first through third aspects wherein, in at least one ofthe plurality of rows, the cooling portions are provided continuously inan elongated shape in the height direction of the blade portion.

A fourth aspect of the present invention is the turbine blade accordingto any of the first through fourth aspects wherein the turbulencepromoting device is formed by a plurality of pin portions that standupright in the areas exposed by the notch portions.

A fifth aspect of the present invention is the turbine blade accordingto any of the first through fourth aspects wherein the turbulencepromoting device is formed by a plurality of step portions that standupright in the areas exposed by the notch portions and that are stackedin rows in the flow direction of the cooling gas.

A sixth aspect of the present invention is the turbine blade accordingto any of the first through fourth aspects wherein the turbulencepromoting device is formed by a plurality of dimple portions that areformed in the areas exposed by the notch portions.

EFFECTS OF THE INVENTION

In the present invention, a plurality of rows of cooling portions havingnotch portions are provided in rows that are stacked in a direction fromthe front edge of a blade to the rear edge of the blade. The row locatedfurthest to the downstream side from among this plurality of rows ofcooling portions forms a turbulence promoting cooling portion that isprovided with turbulence promoting devices and cools by means ofturbulence. All of the other rows form film cooling portions that form afilm cooling layer. As a consequence, according to the presentinvention, the turbulence of the cooling gas is promoted by theturbulence promoting cooling portions so that a convective heat transferis promoted in the turbulence promoting cooling portions, and a filmcooling layer is formed by the cooling gas flowing out from the filmcooling portions. This enables film cooling to be performed. Namely,according to the present invention, in rear edge areas of the bladeportions, a convective heat transfer with the film cooling gas whosetemperature is lower than that of the main flow gas is promoted by theturbulence promoting cooling portions. As a result, rear edge portionsof a blade portion can be cooled efficiently. Accordingly, according tothe present invention, by providing notch portions that form a filmseparately from notch portions that have a structure that promotes thetransfer of heat, it is possible to suppress any reduction in the filmcooling efficiency, and to improve the heat transfer rate between theblade portions and the cooling gas. As a result, the cooling efficiencyof the area around the rear edge of a blade portion can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a turbine blade according to anembodiment of the present invention.

FIG. 2A is a cross-sectional view of a turbine blade according to anembodiment of the present invention.

FIG. 2B is a cross-sectional view of a turbine blade according to anembodiment of the present invention.

FIG. 3A is a perspective view showing in enlargement principal portionsof a turbine blade according to an embodiment of the present invention.

FIG. 3B is a perspective view showing in enlargement principal portionsof a turbine blade according to an embodiment of the present invention.

FIG. 4A is an enlarged perspective view showing a variant example of aturbine blade according to an embodiment of the present invention.

FIG. 4B is an enlarged perspective view showing a variant example of aturbine blade according to an embodiment of the present invention.

FIG. 5 is a plan view showing a variant example of a turbine bladeaccording to an embodiment of the present invention.

BEST EMBODIMENTS FOR IMPLEMENTING THE INVENTION

Hereinafter, an embodiment of a turbine blade according to the presentinvention will be described with reference made to the drawings. Notethat in the drawings the scale of each component has been suitablyaltered in order to make each component a recognizable size.

FIG. 1 is a perspective view of a turbine blade 1 of the presentembodiment. FIGS. 2A and 2B are cross-sectional views of the turbineblade 1, FIG. 2A is a cross-sectional view taken along a line A-A inFIG. 1, and FIG. 2B is a cross-sectional view taken along a line B-B inFIG. 1. As is shown in FIG. 1, the turbine blade 1 of the presentembodiment is provided with a blade portion 2, a root portion 3, andcooling portions 4.

As is shown in FIGS. 2A and 2B, the blade portion 2 is set in a bladeshape having a front edge 21 (i.e., a blade front edge), a rear edge 22(i.e., a blade rear edge), a ventral side blade surface 23 (i.e., ablade belly), and a rear side blade surface 24. In addition, an internalportion 25 (i.e., a blade interior portion) of the blade portion 2 isprovided with a hollow portion into which a cooling gas can beintroduced. This blade portion 2 is positioned with the front edge 21facing towards the upstream side of the fluid body. As a result, a flowin which the fluid body flows from the front edge 21 towards the rearedge 22 is formed on the surfaces of the ventral side blade surface 23and the rear side blade surface 24 of the blade portion 2. Note that inthe following description, a flow from the front edge 21 towards therear edge 22 along the surfaces of the ventral side blade surface 23 andthe rear side blade surface 24 is referred to as a main flow.

The root portion 3 supports the blade portion 2, and is fixed to aturbine disk. Note that the root portion 3 has an internal flow path(not shown). Cooling gas is supplied to the internal portion 25 of theblade portion 2 through this internal flow path in the root portion 3.

The cooling portions 4 discharge the cooling gas introduced into theinternal portion 25 of the blade portion 2 onto the ventral side bladesurface 23 side of the rear edge 22 side, and cool the rear edge areaincluding the rear edge 22. These cooling portions 4 have notch portions41 that are formed on the ventral side blade surface 23 side, and thesenotch portions 41 form slots 42. Moreover, the cooling portions 4 havethrough holes 43 that are provided in the wall portion on the front edge21 side of the slot 42, and that penetrate into the interior portion 25of the blade portion 2. These through holes 43 discharge cooling gasinto the notch portions 41. In this manner, the cooling portions 4 ofthe turbine blade 1 of the present embodiment have notch portions 41that discharge the cooling gas introduced into the internal portion 25of the blade portion 2 onto the ventral side blade surface 23 side.

Moreover, as is shown in FIG. 1, the turbine blade 1 of the presentembodiment is provided with two rows (i.e., a plurality of rows) of thecooling portions 4 that are stacked in a direction from the front edge21 towards the rear edge 22. Each of these rows is formed by a pluralityof the cooling portions 4 that are placed discretely from each other inthe height direction of the blade portion 2 (i.e., in the top-bottomdirection of the sheet of paper on which FIG. 1 is shown) and at equaldistances from each other. Moreover, as is shown in FIG. 1, the coolingportions 4 that form the row on the front edge 21 side, and the coolingportions 4 that form the row on the rear edge 22 side are offset fromeach other in the height direction of the blade portion 2. As a result,the cooling portions 4 are arranged in a zigzag pattern.

In addition, in the turbine blade 1 of the present embodiment, thecooling portions 4 that form the row on the front edge 21 side make upfilm cooling portions 4A, while the cooling portions 4 that form the rowon the rear edge 22 side make up film cooling portions 413.

FIG. 3A is an enlarged perspective view of a film cooling portion 4A. Asis shown in FIG. 3A, the film forming portion 4A is provided with a flatarea R that is exposed by the notch portion 41. This film coolingportion 4A forms a film cooling layer using the cooling gas that isdischarged from the through hole 43, and thereby performs film cooling.In other words, the film cooling portion 4A forms a film cooling layerin the area R that is exposed by the notch portion 41, and is therebyable to perform film cooling. Namely, the area around the rear edge ofthe blade portion 2 is able to be cooled by this structure.

FIG. 3B is an enlarged perspective view of a film turbulence promotingcooling portion 4B. As is shown in FIG. 3B, the turbulence promotingcooling portion 4B is provided with a plurality of pin portions 44(i.e., turbulence promoting devices) that stand upright on the flat areaR that is exposed by the notch portions 41. This turbulence promotingcooling portion 4B promotes turbulence as a result of the laminar flowexpelled from the through hole 43 colliding with the plurality of pinportions 44. Namely, using this turbulence, it is possible to promote aconvective heat transfer between the film air and the blade portion.Moreover, as is shown in FIG. 3B, the plurality of pin portions 44 arearranged in a zigzag pattern on the area R. The height of each pinportion 44 is set such that the pin portions 44 do not protrude abovethe surface of the ventral side blade surface 23 in order to avoid anycollision with the aforementioned main flow. Note that, as is shown inFIG. 3B, in the present embodiment all of the pin portions 44 are set atthe same height, however, it is not essential for the height of the pinportions 44 to be standardized.

In the turbine blade 1 of the present embodiment that is constructed inthe above-described manner, the plurality of rows of cooling portions 4that have the notch portions 41 are arranged so as to form rows that arestacked from the front edge 21 towards the rear edge 22. In addition,the row from among the plurality of rows of cooling portions 4 that islocated on the rear edge 22 side forms the turbulence promoting coolingportions 4B, while the row on the front edge 21 side forms the filmcooling portions 4A. Because of this, according to the turbine blade 1of the present embodiment, a convective heat transfer is promoted by theturbulence promoting cooling portions 4B, and a film cooling layer isformed by the film cooling portions 4A. Namely, because the convectiveheat transfer that is generated between the film cooling gas whosetemperature is lower than that of the main flow gas and the bladeportion is promoted by the turbulence promoting cooling portion, rearedge portions of a blade portion can be cooled efficiently. Accordingly,according to the present invention, by providing the notch portions thatform the film cooling layer separately from the notch portions that havea structure that promotes the transfer of heat, it is possible tosuppress any reduction in the film cooling efficiency, and to improvethe heat transfer rate between the blade portions and the cooling gas.As a result, the cooling efficiency of the area around the rear edge ofa blade portion can be improved.

Moreover, in the turbine blade 1 of the present embodiment, the coolingportions 4 that form the row furthest to the rear edge 22 side form theturbulence promoting cooling portions 413. Normally, the rear side bladesurface of the rear edge side of the blade portion is where thetemperature of the blade surface is most easily increased, and it isnecessary to strengthen the cooling in this region. Namely, by providingnotch portions in the wall surface of the side of the blade portionhaving this region that is cooled (i.e., the blade belly side), it ispossible to achieve a heat transfer in this region at a high heattransfer rate with cooling gas at the lowest possible temperature.Furthermore, as in the turbine blade 1 of the present embodiment, as aresult of the cooling portions 4 that form the row furthest to the rearedge 22 side forming the turbulence promoting cooling portions 413, theeffects of this turbulence on the downstream side of the flow can bereduced. Namely, it is possible to prevent any deterioration in the filmcooling efficiency and to improve the heat transfer rate between theblade portion and the cooling gas.

Moreover, in the turbine blade 1 of the present embodiment, a structureis employed in which turbulence is created by the pin portions 44.Because of this, turbulence can be created by means of a simplestructure.

Note that, as is shown, for example, in FIG. 4A, instead of the pinportions 44 it is possible to provide a plurality of step portions 45(i.e., turbulence promoting devices) that stand upright on the flat areaR that is exposed by the notch portions 41, and that are arranged in theflow direction of the cooling gas. When this plurality of step portions45 are used, the cooling gas discharged from the through holes 43 isable to collide with the step portions 45 so that turbulence is promotedby this structure as well. Namely, turbulence can be promoted by meansof a simple structure.

Moreover, as is shown, for example, in FIG. 4B, instead of the pinportions 44 it is possible to provide a plurality of dimple portions 46(i.e., turbulence promoting devices) that are formed in the area that isexposed by the notch portions 41. When this plurality of dimple portions46 are used, the cooling gas discharged from the through holes 43 flowsinto the dimple portions 46 so that turbulence is generated by thisstructure as well. Namely, turbulence can be promoted by means of asimple structure.

Moreover, in the turbine blade 1 of the present embodiment, theplurality of cooling portions 4 that make up a row are placed discretelyfrom each other in the height direction of the blade portion. As aconsequence, it is possible to leave a thick area of the blade portionbetween cooling portions 4 so that the strength of the turbine blade 1remains unimpaired.

Note that as is shown, for example, in FIG. 5, it is also possible toprovide a cooling portion 4 (i.e., the cooling portion 4A in FIG. 5)that is provided continuously in an elongated shape in the heightdirection of the blade portion. By employing this type of coolingportion 4, it is possible to cool an even broader range in the heightdirection of the blade portion. However, if the cooling portion 4 isformed in an elongated shape, then the surface area of the apertures ofthe through holes also increases. Namely, there is a possibility thatthe flow rate of cooling gas that is discharged from a row that isformed by this cooling portion 4 that is provided continuously in anelongated shape will be greater than the flow rate of cooling gasdischarged from a row that is formed by cooling portions 4 that arearranged discretely. Because of this, if the cooling portion 4 is formedin an elongated shape, it is preferable for the surface area of theapertures of the through holes in the cooling portion 4 that is providedcontinuously in an elongated shape to be narrowed down, so thatsufficient cooling gas can be discharged from the cooling portions 4that are arranged discretely.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Combinations orthe like of the respective members shown in the aforementioned examples,and can be variously changed in a scope of not depending from the gistof the present invention based on the design request or the like.

For example, the typical view of a turbine blade in FIG. 1 shows amoving blade. However, the present structure can also be applied to astationary blade.

Moreover, in the turbine blade 1 of the present embodiment, two rows ofcooling portions 4 are provided so as to form rows that are stacked inthe flow direction of the main flow. However, the present invention isnot limited to this and it is also possible to provide the plurality ofrows of cooling portions 4 in three or more rows in the flow directionof the main flow. In this case, of the plurality of rows of coolingportions 4 of the present invention, those cooling portions in the rowlocated furthest to the downstream side form the turbulence promotingcooling portions 4B, while the cooling portions in at least one of theother rows form the film cooling portions 4A.

Moreover, in the turbine blade 1 of the present embodiment, the coolingportions 4 are arranged in a zigzag pattern. However, the presentinvention is not limited to this and it is also possible for the coolingportions 4 to be arranged in a lattice configuration. Moreover, it isalso possible that the through holes 43 are not formed in the turbulencepromoting cooling portions 4B.

INDUSTRIAL APPLICABILITY

According to the present invention, by providing notch portions thatform a film separately from notch portions that have a structure thatpromotes the transfer of heat, it is possible to suppress any reductionin the film cooling efficiency, and to improve the heat transfer ratebetween the blade portions and the cooling gas. As a result, the coolingefficiency of the area around the rear edge of a turbine blade can beimproved.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 . . . Turbine blade-   2 . . . Blade portion-   21 . . . Front edge (Blade front edge)-   22 . . . Rear edge (Blade rear edge)-   23 . . . Ventral side blade surface (Ventral side)-   24 . . . Rear side blade surface (Rear side)-   25 . . . Internal portion (Internal portion of the blade portion)-   4 . . . Cooling portion-   4A . . . Film cooling portion (Cooling portion)-   4B . . . Turbulence promoting cooling portion (Cooling portion)-   41 . . . Notch portion-   42 . . . Slot-   43 . . . Through hole-   44 . . . Pin portion (Turbulence promoting device)-   45 . . . Step portion (Turbulence promoting device)-   46 . . . Dimple portion (Turbulence promoting device)

What is claimed is:
 1. A turbine blade that is provided with a pluralityof rows of cooling portions that have notch portions that dischargecooling gas that has been introduced into an internal portion of a bladeportion onto a ventral side blade surface, and that are formed in rowsthat are stacked in a direction between the blade front edge and theblade rear edge, comprising: turbulence promoting cooling portions thatare provided in the row located closest to the downstream side fromamong the plurality of rows, and that have turbulence promoting devicesin areas exposed by the notch portions; and film cooling portions thatare provided in at least one of other rows from among the plurality ofrows, and that form a film cooling layer in the areas exposed by thenotch portions.
 2. The turbine blade according to claim 1, wherein, inat least one of the plurality of rows, the plurality of cooling portionsare placed discretely from each other in the height direction of theblade portion.
 3. The turbine blade according to claim 1, wherein, in atleast one of the plurality of rows, the cooling portions are providedcontinuously in an elongated shape in the height direction of the bladeportion.
 4. The turbine blade according to claim 1, wherein theturbulence promoting device is formed by a plurality of pin portionsthat stand upright in the areas exposed by the notch portions.
 5. Theturbine blade according to claim 1, wherein the turbulence promotingdevice is formed by a plurality of step portions that stand upright inthe areas exposed by the notch portions and that are stacked in rows inthe flow direction of the cooling gas.
 6. The turbine blade according toclaim 1, wherein the turbulence promoting device is formed by aplurality of dimple portions that are formed in the areas exposed by thenotch portions.